Cards that set a creature's power and/or toughness to specific values, like Turn to Frog, were always confusing because while the card said the creature "became 1/1," this was often not true because of other continuous effects. Things like Auras, +1/+1 counters, and Giant Growth still applied to the creature. It was definitely weird when your creature that just became 1/1 was actually 3/5. To help alleviate this confusion, we came up with a new term: base power and toughness. Cards that set a creature's power and toughness to a specific value will now use this new template to reinforce that you're essentially just changing the numbers in the lower right corner. Other effects may still apply. (Special shout-out to former Magic developer Max McCall for convincing us to get the ball rolling on this one.)

In all, 47 cards were updated. There are many variations, and it would be unwieldy to list them all here. If you search Gatherer for the rules text "base," you'll find 48 cards. Just ignore Phyrexian Debaser.

Notably, cards that animated themselves, like Mutavault, and cards that were likely to affect noncreatures, like March of the Machines, did not receive an update. Our research showed that very few people were confused about Mutavault was 3/3 if you activated its last ability while controlling Glorious Anthem, for example.